Request
Please explain how 2 StatefulSets are createad automatically when deploying prometheus-operator Helm chart. It'd be awesome if you could point me to the piece of the chart that pulls those 2 statefulsets.
Reproduce
$ helm repo add stable https://kubernetes-charts.storage.googleapis.com
$ helm install prom-op stable/prometheus-operator
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
alertmanager-prom-op-prometheus-operator-alertmanager-0 2/2 Running 0 49m
prom-op-grafana-78c44f8bc8-nvf45 2/2 Running 0 49m
prom-op-kube-state-metrics-db84fc9d-smsk6 1/1 Running 0 49m
prom-op-prometheus-node-exporter-87t5g 1/1 Running 0 49m
prom-op-prometheus-operator-operator-8554b8f87-6hv9d 2/2 Running 0 49m
prometheus-prom-op-prometheus-operator-prometheus-0 3/3 Running 1 49m
$ kubectl get sts
NAME READY AGE
alertmanager-prom-op-prometheus-operator-alertmanager 1/1 51m
prometheus-prom-op-prometheus-operator-prometheus 1/1 51m
As you can see 2 statefulsets are created, but I can't seem to understand how they get created.
Context
There is a custom tailored prometheus-operator on my hands that does not pull 2 statefulsets for some reason. So far my analysis did not yield any clear understanding. All I end up with is grafana, kube-state-metrics, node-exporter and operator, and no statefulsets.